Antikythera Mechanism

February 27, 2009

Readers may recall that I volunteer a few hours a week in the Webster Institute for the History of Astronomy at Adler Planetarium & Astronomy Museum in Chicago. The Institute is home to one of the world's major collections of early astronomical instruments, rare and modern astronomy books, and works on paper, and these days curators and staff are busy putting together a new exhibit commemorating the 400th anniversary of the telescope's use in astronomy. The exhibit opens in May and I'm already looking forward to the event.

Recently, two other events sharing Chicago and either direct or indirect Adler connections also held my attention. The first came across the news wires from the 2009 annual meeting of the American Association for the Advancement of Science (AAAS), which was held in Chicago February 12-16. Dr. Alan Boss of the Department of Terrestrial Magnestism at the Carneigie Institution for Science in Washington, DC (a very attractive place to work!) spoke on "The Search for Living Planets" at a symposium on planet origins and evolution. Alan Boss is an expert on exoplanets and part of the Science Working Group on NASA's Kepler Mission. He's also a member of something called the NASA External Independent Readiness Board for the Navigator Program, which oversees all NASA missions concerned with the detection and description of "habitable" planets.

The External Independent Readiness Board. I like the sound of that.

Anyway, Boss made news last week because in his talk he mentioned that there could be a hundred billion Earth-like planets in our own galaxy. In an interview with the BBC, he added:

"Not only are they probably habitable but they probably are also going to be inhabited. But I think that most likely the nearby 'Earths' are going to be inhabited with things which are perhaps more common to what Earth was like three or four billion years ago."

The idea of there being a hundred billion Earth-like planets in our galaxy is staggering considering the Milky Way is just one of perhaps 80-100 billion galaxies in the known universe. This gives new meaning to the word perspective. And speaking of perspective, you can also get a completely current one focused on the drama and science of searching for habitable worlds in Boss's new book, The Crowded Universe: The Search for Living Planets (Basic Books, 2009). Published earlier this month, The Crowded Universe is truly an insider's account.

Another book published in February is behind last week's second Chicago connection, this one with a direct path to an Adler Planetarium conference room.

On the 17th, Jo Marchant, a London-based freelance journalist and editor for New Scientist magazine, in town for the AAAS meeting, came to the Adler to give a lunchtime talk on the amazing instrument called the "Antikythera mechanism." The largest part of the device was recovered by sponge divers in 1900 from the wreckage of an ancient Roman merchant ship near the Greek island of Antikythera. On examination it was found to contain inscriptions and extensive gearworks. Ever since, its details have been intensely studied in an effort to determine what the mechanism was designed to do and how it worked. This remarkable story of painstaking detective work, and its results, is the subject of Marchant's first book, Decoding the Heavens: A 2,000-Year-Old Computer--and the Century-Long Search to Discover Its Secrets (Da Capo Press, 2009).

I'd heard about the mechanism but I knew very little about it before Marchant's presentation. As it turns out, scholars today have an informed, though far from complete, idea about what the instrument did. The main title of her book, Decoding the Heavens, suggests its purpose as well as the process behind its gradual decipherment. BTW, the largest fragment of the artifact, displayed along with others in the National Archeological Musuem in Athens, looks like this:

Credit: Jo Marchant. Used with permission.

The device, which dates to approximately 70 BC, was apparently made of bronze and housed in a wooden case. In addition to Marchant's book, information about the latest findings and reconstructed models of the mechanism are available from New Scientist and The Antikythera Research Project, an international group of scholars focused on unlocking the still-remaining secrets of the device.

No doubt the astronomers in the conference room enjoyed the talk as much as I did. The mechanism reveals deep insights about ancient Greek astronomy and its use of Babylonian astronomical data. The instrument's extensive gearworks demonstrate (among other things) the relationship between the solar year and lunar month, as well as planetary and eclipse cycles. According to the Antikythera Mechanism Research Project, its purpose was "to position 'heavenly bodies' with respect to the 'celestial sphere,' [of ancient Greek cosmology] with reference to the observer's position on the surface of the Earth."

For these and other reasons the device is generally thought to represent the world's oldest analog computer. But during her presentation Marchant mentioned another view: Alexander Jones of NYU's Institute for the Study of the Ancient World recently suggested the mechanism is more like a "simulator" than a computer, demonstrating how the then-known universe was thought to work.

Whatever its true function, historians of science appreciate what this unique instrument reveals about the astonishing mathematical and engineering skills of the Ancient Greeks. The Antikythera Mechanism Research Project understatedly says "it precedes any other known clockwork mechanisms of similar complexity by more than a millennium." Researchers think other instruments like it were made in the Ancient world, but the one recovered off Antikythera is the only known example on the planet.

As for myself, I thoroughly enjoyed the Chicago and Adler connections mentioned above. They remind me of past and present associations with subjects I've long been interested in: archaeology, the conservation and preservation of early material culture, documentary research, the search for life beyond Earth, and our place in the cosmos.

Finding that place is a large part of what human life is about, regardless of our position on Earth and the meanings we attach to it.